淀山湖底泥氮磷释放通量研究

Fluxes of Nitrogen and Phosphorus Releasing from Sediment in Dianshan Lake

水体中氮、磷元素的含量是影响藻类生长的重要因子，来源可分为外源性和内源性，而底泥氮、磷释放是内源性氮．磷的重要组成。为了解城市浅水型湖泊中底泥内源氮．磷释放过程及其规律，根据淀山湖底泥状况，在湖的进水口2个采样点，湖中1个采样点、湖的出水口1个采样点分别采集底泥，通过在室内模拟不同的pH值、温度、扰动3个环境因子对底泥氮、磷释放的影响，研究浅水湖水体中底泥氮，磷释放因素及其机理。结果表明，淀山湖底泥具有明显的TP释放特性；温度会影响底泥的氮、磷释放量．且温度越高，TN、TP释放通量越大；扰动上覆水体会加快底泥氮、磷的释放，扰动越大，氮、磷释放通量越大；PH升高会加快底泥氮、磷释放通量；淀山湖进水口处底泥污染较严重，湖中心的底泥磷含量也相当高，在出水口处的底泥受污染较轻。

Contents of nitrogen and phosphorus in water are essential to affect the algae＇s growth. The sources of nitrogen and phosphorus can be categorised into external and internal ones. Nitrogen and phosphorus releasing from sediment is regarded as a major component of the internal source. To know the nitrogen and phosphorus releasing process and patterns of the internal source in urban shallow lakes, sediment was collected at two spots at the inlet, one spot within the lake and other two at the outlet of Dianshan Lake. Through a laboratory simulation of the effects of three environmental factors （pH value, temperature and perturbance） on nitrogen and phosphorus releasing from sediment, the release mechanism in shallow lakes has been studied. It was indicated that sediment in Dianshan Lake had an evident feature to release nitrogen and phosphorus, and those environmental factors could make influences： the higher the temperature, or the more the perturbation in the water column above sediment, or the higher the pH value was, the greater the fluxes of nitrogen and phos- phorus releasing could be. In Dianshan Lake, sediment at the inlet has been seriously contaminated, in the centre of the lake had rather high level of phosphorus, but at the outlet been relatively less polluted.